: having a monovalent organic group and especially one CnH2n+1 (such as methyl) derived from an alkane (such as methane)
: a compound of one or more alkyl groups with a metal
mercury alkyls
Examples of alkyl in a Sentence
Recent Examples on the Web
Amber Smith, Discover Magazine, 24 Feb. 2023
Perfluorinated and polyfluorinated alkyl substances, or PFASs, are considered indestructible chemicals.
—Lars Fischer, Scientific American, 31 Jan. 2022
The alkyl side chain is the driving force behind a cannabinoid's effects on humans.
—Kristen Rogers, CNN, 3 Feb. 2020
Richard Stone, Science | AAAS, 19 Mar. 2018
The alkyl chloride and organophosphate precursors are toxic, but not nearly to the degree of VX, which was developed in the 1950s for chemical warfare and is the most potent of all nerve agents.
—Ben Otto, WSJ, 6 Oct. 2017
Dragna recommends finding personal care products that contain surfactants from the alkyl polyglycosides instead, the most common of which is decyl glucoside, because the head group is a sugar instead of a sulfate.
—Ajc Homepage, ajc, 28 Aug. 2017
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Adjective
This power is owed in part to its unique structure; the unusually long alkyl side chains of seven carbon atoms give an edge over conventional THC's five-carbon makeup.
—Amber Smith, Discover Magazine, 24 Feb. 2023
Perfluorinated and polyfluorinated alkyl substances, or PFASs, are considered indestructible chemicals.
—Lars Fischer, Scientific American, 31 Jan. 2022
The alkyl side chain is the driving force behind a cannabinoid's effects on humans.
—Kristen Rogers, CNN, 3 Feb. 2020
Noun
The second concern, Radić says, is that A-232’s alkyl amine group could enable it to target other enzymes in addition to AChE—and that raises the specter of severe symptoms arising months or years after exposure.
—Richard Stone, Science | AAAS, 19 Mar. 2018
The alkyl chloride and organophosphate precursors are toxic, but not nearly to the degree of VX, which was developed in the 1950s for chemical warfare and is the most potent of all nerve agents.
—Ben Otto, WSJ, 6 Oct. 2017
Dragna recommends finding personal care products that contain surfactants from the alkyl polyglycosides instead, the most common of which is decyl glucoside, because the head group is a sugar instead of a sulfate.
—Ajc Homepage, ajc, 28 Aug. 2017
Cite this Entry
“Alkyl.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/alkyl. Accessed 4 Nov. 2025.
Copy CitationMedical Definition
alkyl
1 of 2 adjective
al·kyl
ˈal-kəl 
: of, relating to, or being an alkyl
alkyl mercurials attack the brain cells—L. J. Goldwater
L. J. Goldwateralkyl
2 of 2 noun1
: a monovalent aliphatic radical CnH2n+1 (as methyl)
broadly
: a monovalent aliphatic, aromatic-aliphatic, or alicyclic hydrocarbon radical
2
: a compound of one or more alkyl groups with a metal
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